Conventionally, as a spectacles-type image display device, for example, a device that includes an image output unit held on the temple side of spectacles and an eyepiece optical unit held adjacent to a lens of spectacles is suggested. Such spectacles-type image display device is configured so that the image light of electronic images to be displayed that is output from the image output unit is incident on an eyeball of a viewer through an eyepiece optical unit so that the viewer can see the images. In such spectacles-type image display device, usually, the electronic images and the background images that transmit a spectacle lens are superimposed and displayed on an eyeball (what is called a see-through display).
As an example of such technology, a device having a concave mirror that obstructs the front view and a plurality of projection lenses (see, for example, JP5303056 (A)) and a device provided with a holographic optical element disposed on a spectacle lens (see, for example, JP2006209144 (A)) are known. In addition, relating to these technologies, as a spectacles-type image display device, for example, a device configured to hold an image output unit by a spectacle frame and the like to allow the image light to enter from outside the spectacle lens (see, for example, JP2001522064 (T)) and a device that constitutes an optical path for allowing the image light to enter in a spectacle lens (see, for example, JP2000511306 (T)) are known.